Method and Installation for the Production of Pellets from Biomass in a Pelletizing Press for Use as Fuel in Furnaces

ABSTRACT

A method and an installation for producing pellets from prepared biomass in a pelleting press for use as fuel in fireplaces. The biomass is made of fibers, shavings or chippings containing cellulose and/or lignocellulose, with or without a binding agent and/or additives, and after being prepared is stored in a biomass bunker. The method includes: biomass discharged from the biomass bunker into a scatter device, a mat made of the biomass having a substantially uniform weight per unit area formed by the scatter device on a molding belt, the mat produced on the molding belt examined by an examining device for defective spots and/or foreign substances, and the mat supplied to a pelleting press. At least parts of the mat or a section of the mat include defective regions and/or foreign substances separated from the method upstream of the pelleting press.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

Germany Priority Application DE 10 2009 016 470.7, filed Apr. 13, 2009 including the specification, drawings, claims and abstract, is incorporated herein by reference in its entirety.

BACKGROUND

1. Field of Embodiments

The embodiments relate generally to a method for producing pellets from prepared biomass in a pelleting press for use as fuel in fireplaces or furnaces. The embodiments further relate to an installation for producing pellets from prepared biomass in a pelleting press for use as fuel in fireplaces or furnaces.

2. Description of Related Art

The production of pellets, also referred to as briquettes or granulates, from fine material or compacted and/or molten material has long been known. Compactors compact material between two rollers, either one or both being formed as a die, and mold the same to form briquettes for use as fuel. Pelletizing by means of extruders and punched disks, optionally with cutting devices disposed downstream, is likewise known to a sufficient extent in the plastics industry or the animal food industry. The production of pellets from preferably comminuted biomass such as wood shavings, dust or the like is likewise known sufficiently and is propagated in the field of renewable energy, at least in Europe, as ground-breaking technology for climate protection.

Currently, biomass is stored in biomass bunkers following its preparation (comminution, screening, drying . . . ) and then discharged with the aid of metering devices and supplied to a pelleting press. Usually, the metering devices used are metering screw conveyors that are, however, not suitable for simultaneously loading several pelleting presses with a constant flow of materials. Therefore, at least one pelleting press, mostly a pan-grinder press comprising an annular die or a two-roller press is disposed for each metering screw conveyor.

It is part of the nature of a metering screw conveyor to additionally compact the biomass, which has already been compacted to a defined degree by its own weight during storage in the biomass bunker, during the conveying process and supply the compacted biomass to a pelleting press. However, clusters of material pose problems in the constant supply to pelleting presses since the former are discharged from the conveyor in lumps in extreme cases. They can even result in problems at the inlet of pelleting presses and a reduction of the maximum throughput per hour if the pelleting presses can no longer comminute the clusters of material or can do so only with great difficulty, and these clusters can block the inlet of the pelleting press on account of their size and can obstruct or even prevent the inflow of biomass into the press gap.

At the same time, the conveyance of lumpy biomass results in a non-uniform loading of the pelleting press which manifests itself, depending on the type of the pelleting press, in increased wear or energy input if irregular driving or compacting forces have to be powered or if locking devices or bearings on shafts are loaded excessively. The separation of the biomass in the biomass bunker or during its metering to the pelleting press poses an additional problem. The conveyance of the biomass results in the problem of so-called lumps of uniform material, for example, dust lumps being formed in addition to coarse lumps of biomass. However, an optimum pellet and the production thereof are particularly characterized by the presence of equal amounts of fine and coarse fractions bonded to each other in a pellet.

The problem confronted in major industrial production planning is that in the case of an enlargement of a two-roller press or a pan-grinder press, the supplying metering screw conveyor would have to be larger by an extremely large factor in order to enable proper loading, or several metering screw conveyors would have to be set up parallel to each other for a large pelleting press. In both solutions, the probability of failure increases significantly and there arise high procurement costs for installation engineering, particularly the control and feedback control systems. Even if only one metering system fails, the entire installation has to be switched off since portions of the pelleting press would otherwise operate in the absence of material, thereby causing increased wear.

According to prior-art production processes, the biomass is dried during its preparation, mostly screened in a classifier, and sent through a gravity separator. The latter application is intended to bring about the separation of higher-density material such as stones, sand or agglutination. However, the disadvantage of a multi-stage gravity separation or other separation processes is that they do not have 100% efficiency, but instead grains of sand or other high-density materials repeatedly remain in the biomass during major industrial use and high throughput of biomass per hour (more than 15 tons/hour). It is also possible for foreign substances to enter into the plant components after the separation process, that is to say, during or after the storage of the biomass in the biomass bunker, as a result of abrasion or wear of plant components in the production process, which foreign substances can result in damaging the pelleting presses. Even a coarse grain of sand in biomass being pressed by a roller press or an annular die comprising associated pan-grinder rollers can damage the press molds. High-quality pellets that are pneumatically placed in the storage facility and/or vehicles and thereafter again in storage rooms at the end-consumer's require a very straight-lined surface structure and are preferably certified by their resistance to abrasion. If the borehole of an annular die or a surface die of a roller press suffers from even slight damage, this results in the serial production of pellets that are slightly elevated. This elevation is sufficient, on the one hand, to cause a notching effect and, on the other hand, to create indentations on other pellets moving past. As a result, the service life of the dies of each pelleting press depends significantly on whether or not the biomass contains any foreign or other detrimental substances that could leave behind signs of damage or indentations on the dies during the pelleting process.

SUMMARY

The embodiments relate generally to a method for producing pellets from prepared biomass in a pelleting press for use as fuel in fireplaces, the biomass being made of fibers, shavings or chippings containing cellulose and/or lignocellulose, with or without a binding agent and/or additives, and the biomass being stored in a biomass bunker following its preparation. The embodiments further relate to an installation for producing pellets from prepared biomass in a pelleting press for use as fuel in fireplaces, the biomass being made of fibers, shavings or chippings containing cellulose and/or lignocellulose, with or without a binding agent and/or additives, and a biomass bunker being disposed for the storage of the biomass following its preparation.

According to one embodiment, a method for the production of pellets from prepared biomass in a pelleting press for use as fuel in fireplaces. The biomass is made of fibers, shavings or chippings containing cellulose and/or lignocellulose, with or without a binding agent and/or additives. The biomass is stored in a biomass bunker following its preparation. The method is characterized by the following process steps: the biomass is discharged from the biomass bunker into a scatter device, a mat made of the biomass having a substantially uniform weight per unit area is then formed by means of the scatter device on a molding belt, the mat produced on the molding belt is examined by means of an examining device for defective spots and/or foreign substances, and the mat is subsequently supplied to a pelleting press, at least parts of the mat or a section of the mat comprising defective spots and/or foreign substances being separated from the method for the production of pellets upstream of the pelleting press.

According to another embodiment, an installation for the production of pellets from prepared biomass in a pelleting press for use as fuel in fireplaces. The biomass is made of fibers, shavings or chippings containing cellulose and/or lignocellulose, with or without a binding agent and/or additives. A biomass bunker is disposed for the storage of the biomass following its preparation. The installation is characterized in that, in the production process downstream of the biomass bunker, a scatter device and a molding belt, which rotates horizontally endlessly in the falling direction of the biomass, is disposed at the discharge side of the scatter device for producing a mat having a substantially uniform weight per unit area, and an examining device for examining defective regions and/or foreign substances in the mat is disposed in the region of the molding belt, and at least one device for separating at least parts of the mat or an entire section of the mats is disposed for separating the defective regions and/or the foreign substances upstream of the pelleting press.

According to yet another embodiment, a method for producing pellets from prepared biomass in a pelleting press for use as fuel in fireplaces. The method comprising the steps of preparing the biomass; storing the biomass in a biomass bunker following the preparation of the biomass; discharging the biomass from the biomass bunker to a scatter device; forming, on a molding belt by using the scatter device, a mat made of the biomass and having a substantially uniform weight per unit area; examining the mat formed on the molding belt for defective regions and/or foreign substances using an examining device; supplying a first section of the mat to the pelleting press; and separating a second section of the mat having the defective regions and/or the foreign substances from the production of the pellets upstream of the pelleting press. The biomass is made of fibers, shavings, or chippings containing cellulose and/or lignocellulose, with or without a binding agent and/or additives.

According to yet another embodiment, an installation for producing pellets from prepared biomass in a pelleting press for use as fuel in fireplaces. The biomass is made of fibers, shavings, or chippings containing cellulose and/or lignocellulose, with or without a binding agent and/or additives. The installation comprises a biomass bunker for storing the biomass following the preparation of the biomass; a scatter device disposed downstream of the biomass bunker; a molding belt disposed at a discharge side of the scatter device, an examining device disposed in a region of the molding belt, and at least one device disposed upstream of the pelleting press. The molding belt is configured to rotate horizontally endlessly. The scatter device is configured to form a mat on the molding belt. The examining device is configured to examine defective regions and/or foreign substances included in a mat. The at least one device is configured to separate at least parts of the mat or an entire section of the mat that contains the defective regions and/or the foreign substances

The object underlying the disclosed embodiments is to provide a method for the production of pellets from biomass, particularly in major industrial production, in which the biomass can be easily but effectively examined, following its preparation, for foreign substances such as stones, sand, inhomogeneities, excessive density or the like upstream of a pelleting press in order to enable a timely separation of the foreign substances before the supply of biomass to a pelleting press and in order to prevent damage to the dies and/or the pan-grinder rollers of a pelleting press. At the same time, the shutdown caused by the required separation process ought to be as short as possible and enable the orderly and uniform supply of biomass to a pelleting press.

In a further embodiment, the method and an independent installation or an installation suitable for carrying out the method ensure the continuous, optimum, uniform, unseparated loading of a pelleting press with biomass without foreign substances over any desired width of the pelleting press.

It has proven to be particularly advantageous that small bodies having a size of 1 mm³ and a higher density relative to the biomass can be detected safely with the aid of a radiography device, preferably a gamma emitter or an X-ray tube assembly. The radiography device preferably disintegrates the weight per unit area of the mat scattered on the molding belt and determines the weight per unit area in the smallest possible grid, for example, of 1 mm², while the continuously scattered mat passes through the radiography device. The density of usable wood (which is not present in the form of bulk material or prepared biomass) is approximately 400 to 800 kg/m³ and common foreign substances such as sand have a density of more than 1.5×10³ kg/m³. If the regular weight per unit area of a scattered and loose mat (containing a lot of air) on a molding belt is, for example, 2 kg/m² with a mat height of 13 mm and a theoretical bulk density of 155 kg/m³ of biomass, then a foreign substance of a size of 1 mm³ and a density of 2×10³ kg/m³ within the mat would significantly increase the weight per unit area in a measuring field of a square millimeter such that this increase is clearly measurable by radiography devices.

Thus, a radiography device is absolutely able to detect if a foreign substance of the smallest shape has not been separated correctly during the preparation of the biomass or if any other foreign substance has subsequently entered into the biomass.

Additional advantageous measures and embodiments will become apparent from the claims and the following description of the drawings. It is to be understood, however, that both the foregoing general description and the following detailed description are exemplary and explanatory only, and are not restrictive of the embodiments as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the present embodiments will become apparent from the following description, appended claims, and the accompanying exemplary embodiments shown in the drawings, which are briefly described below.

FIG. 1 is a diagrammatic illustration of a known installation for producing pellets.

FIG. 2 is a diagrammatic illustration of an exemplary installation, particularly for carrying out a method.

FIG. 3 is an enlarged illustration of the disintegrating device of FIG. 2 disposed downstream of the molding belt in the falling direction of the mat.

FIG. 4 is an enlarged illustration of an exemplary disintegrating device disposed at a discharge side of a molding belt with various separating defective spots of the mat or the biomass, and/or foreign substances.

FIG. 5 is an enlarged illustration of exemplary disintegrating rollers of the disintegrating device shown in FIG. 2.

FIG. 6 shows another installation for producing pellets with the aid of a preferred embodiment of a pelleting press with outwardly disposed pan-grinder rollers on a rotating annular die and an optimum distribution of the biomass over the length and width of the pelleting press by the molding belt and a disintegrating device disposed downstream together with an examining device for the mat made of biomass and disposed on the molding belt.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Presently preferred embodiments are illustrated in the drawings. An effort has been made to use the same reference numbers throughout the drawings to refer to the same or like parts.

As shown in FIG. 1, the known process of producing pellets is as follows: prepared and sorted biomass 1 is stored in a biomass bunker 3 and discharged therefrom. The stored biomass can be discharged with the aid of an intermediate conveyor or directly by means of a metering device 4 formed as a metering screw conveyor 19. If necessary, the biomass 1 can be treated in the metering screw conveyor 19 with steam by means of a vaporization device 13 or optionally also examined in an intermediate station for defective spots defined by foreign substances that are detrimental to a pelleting press. The biomass falls out of the metering screw conveyor 19 in the discharge area and is now pressed to form pellets 9 with the aid of a pelleting press 2 comprising one or two rollers in this example.

As shown in FIG. 2, the metering device 4 is not formed as a metering screw conveyor 19, but instead as a scatter device 6 that deposits or scatters the biomass 1 with the most uniform possible weight per unit area on a molding belt 7. The biomass 1 undergoes an optimum disintegration here and it is deposited loosely on an intermediate conveyor, that is to say, the molding belt 7. Advantageously, the biomass 1 is now present in the form of a mat 8 of uniform weight per unit area and can be supplied with a uniform weight per unit area, depending on the width of the molding belt and thus over any desired width, to an oversized pelleting press, for example. A control or regulating device (not illustrated) is preferably provided which ensures the optimum entry of the biomass 1 deposited on the molding belt 7 into the pelleting press depending on the possible production volume and the speed of the roller press or a grinding press. Here too, a vaporization device 13 can also be provided through which the molded belt 7 and the mat 8 pass, the molding belt 7 being formed as a screening belt in this case. Advantageously, the mat 8 can be examined on the molding belt by means of an examining device 11, preferably a weighing device, or more preferably a radiography device for determining the weight per unit area of the mat 8 in order to determine any irregularities in the biomass 1. These irregularities are, for example, defective regions 25 of the mat 8 and/or foreign substances 26 and/or inhomogeneities and/or excessive density with properties detrimental to the pelleting press 2. Particularly with the aid of a radiography device formed as the examining device 11, variations in the weight per unit area can be determined that are sought by means of a single grain of sand having the size of a cubic millimeter since a high resolution is possible with the use of radiography devices and the variation in the weight per unit area due to a grain of sand that has not been removed by a screening or gravity separation during the preparation of biomass can be detected in relation to the biomass 1 of the mat 8.

In a preferred exemplary embodiment, the discharged mat 8 is supplied to a disintegration device 5 before the biomass 1 enters into the pelleting press 2 and is pressed to form pellets 9. This makes sense particularly when the mat 8 has been compacted with the aid of a prepress 12 disposed upstream of the examining device 11, but can also be carried out as a matter of principle. In the case of a determined defective region 25 or defective spot 25 of the mat 8, the defective spot 25 is disposed of in a refuse chute 16 in that the molding belt 7 changes the discharge area of the mat 8 by means of a molding belt-retraction system 17.

FIG. 3 is an enlarged illustration of the disintegrating device 5 which comprises at least one spoke roller 14, four spoke rollers 14 in this case. For an improvement of disintegration, at least one forwarding roller 15 can be provided in the falling direction upstream of the spoke rollers 14; in this preferred exemplary embodiment, there are four forwarding rollers 15 that ensure for a pre-separation in a stepped manner. The rotational direction of the spoke rollers is marked in the drawing by way of example.

FIG. 4 is an enlarged illustration of another embodiment of the disintegrating device 5 disposed on a molding belt 7 shown in FIG. 2. Here, a milling roller 10 rotates at an appropriate speed in the clockwise direction in the drawing and separates the mat 8 directly at the end of the metering device 4. The disintegrating device 5 distributes the biomass 1 over a predetermined area and the latter is then uniformly supplied to the pelleting press 2. Preferably, only biomass 1 that has been sieved to a size of more than 0.3 mm of screening mesh width during its preparation is used.

As can be further inferred from FIG. 4, there are various combinable options for removing parts of the mat 8 or an entire section of the mat 8 from the production process and transferring the same to a refuse chute 16. For this purpose, a suction device 31 and/or a removing device 32 are disposed in the region of the molding belt 7, both the suction device 31 and/or the removing device 32 being adjustable in height above the molding belt 7 in the direction extending vertically or angularly relative to the molding belt 7 by means of actuating drives. While the suction device 31 removes parts of the mat 8 only by means of concentrated suction, similar to a vacuum cleaner, for which purpose it can be displaced by additional actuating drives transversely relative to the travel direction of the mat 8, said suction device can also remove the entire mat 8 from the molding belt when provided with an extra-wide design. The removing device 32 in the exemplary embodiment shown in FIG. 4 comprises a roller rotating in the anticlockwise direction and it combs the mat 8 against the conveying direction of the molding belt 7 into a likewise height-adjustable pick-up device that is preferably likewise formed as a suction device. FIG. 4 also clearly shows the manner in which the examining device 11 detects a defective region 25 or the existence of a foreign substance 26 in the mat 8. An examining device 11 preferably comprises a radiography device comprising an emitter 30 and a detector 33 including an associated evaluating unit (not illustrated). Preferably, an X-ray tube assembly or a gamma emitter is used. Subsequently, the entire mat 8 or only parts selected over the width thereof can be separated after discharge from the molding belt 7 by arranging pneumatic nozzles 27 and/or a switching system 28 and/or a suction device 31 (not shown in the falling area of the mat). The switching system 28 can comprise one or more selectively switchable flaps over the width of the mat 8. The arrows indicated by the dashed lines show the path of the separated mat parts or the defective regions of the mat 8 in the discharge area downstream of the molding belt 7. The pneumatic nozzles 27 can also be activated selectively over the width of the mat. For this purpose, the travel of the determined defective regions 25 or a foreign substance 26 is tracked by means of a tracking system and the flaps of the switching system 28 or the pneumatic nozzles 27 are activated in time and for a sufficiently long duration.

FIG. 5 is an enlarged side view of possible exemplary of spoke rollers 14 that comprise, in the upper detail drawing, straight-lined spokes 22 that can also be bent in a shovel-shaped manner. In the central illustration, the spokes 22 are shown in the form of connections between the externally located disks of the spoke roller 14, the connections being disposed in a radius and being preferably made of connecting pipes or rods. The lower detail drawing shows a disintegrating roller or the spoke roller 14 comprising spikes 23. In a two-stage design of the disintegrating device, shown in FIG. 3 in particular, forwarding rollers 15 are disposed in the falling area of the biomass 1 upstream of the disintegrating rollers or the spoke rollers 14. It is naturally possible within the scope of the embodiments to also use other disintegrating methods or devices in order to achieve the goal of proper disintegration and/or distribution of the biomass upstream of or above a pelleting press 2.

FIG. 6 shows yet another variant of a pelleting press 2 by way of example which comprises a rotating annular die 24 and one of more pan-grinder rollers 21 resting against the latter. In a particularly preferred embodiment, the mat 8 disposed on the molding belt 7 is scattered over a preferably equal length of the annular die 24 or the pan-grinder rollers 21 and discharged above the pelleting press 2. The mat 8 breaking during the discharge or falling process is then disintegrated by means of at least one disintegrating roller, four spoke rollers 14 in the present example, and distributed uniformly over the distribution section 20. In the case of a particularly high throughput or other applications, it may be necessary to provide the disintegrating device 5 with a two-stage design. For this purpose, forwarding rollers 15 are provided in the falling direction of the biomass upstream of the disintegrating rollers, which are adapted to suit the application or are provided with a similar structural geometry as the spoke rollers 14 shown in FIG. 5. Since a distribution of the mat has already taken place in the longitudinal extension of the pelleting press due to the uniform mat produced and preferably optimized in terms of its weight per unit area, the mat is now distributed approximately over the diameter or the distribution section 20 and simultaneously disintegrated homogeneously so that no separated fine and coarse material or clusters arrive into the pressing zone of the pelleting press 2. Screens 34 can also be disposed in the disintegrating device 5 as an alternate to the guide flaps 18.

It is evident that the disintegrating device 5 can disintegrate the scattered mat 8 shown in FIGS. 2 and 6 irrespective of the feed motion of the molding belt 7, the height of the mat 8 or also the density of the mat 8. This holds true particularly when the biomass 1 displays a bonding tendency as a result of a previous vaporization and/or water-spraying process.

Exemplary Embodiments

According to a first embodiment, a method for the production of pellets 9 from prepared biomass 1 in a pelleting press 2 for use as fuel in fireplaces, the biomass 1 being made of fibers, shavings or chippings containing cellulose and/or lignocellulose, with or without a binding agent and/or additives, and the biomass 1 being stored in a biomass bunker 1 following its preparation, which method is characterized by the following process steps: the biomass 1 is discharged from the biomass bunker 3 into a scatter device 6, a mat 8 made of the biomass 1 having a substantially uniform weight per unit area is formed by means of the scatter device 6 on a molding belt 7, the mat 8 produced on the molding belt 7 is examined by means of an examining device 11 for defective spots 25 and/or foreign substances 26, and the mat 8 is supplied to a pelleting press 2, at least parts of the mat 8 or a section of the mat 8 comprising defective regions 25 and/or foreign substances 26 being separated from the method for the production of pellets 9 upstream of the pelleting press 2.

According to a second embodiment, the method according to the first embodiment characterized in that defective regions 25 of the mat 8 and/or foreign substances 26 and/or inhomogeneities and/or excessive density with properties detrimental to the pelleting press 2 are determined and separated.

According to a third embodiment, the method according to the first embodiment or the second embodiment characterized in that a weighing device and/or a radiography device is used as the examining device 11.

According to a fourth embodiment, the method according to one of more of the preceding embodiments characterized in that the radiography device determines the weight per unit area of the mat 8 in a grid of a square millimeter for detecting defective regions 25 or foreign substances 26.

According to a fifth embodiment, the method according to one or more of the preceding embodiments characterized in that sections of defective regions 25 of the mat 8 or at least parts of the mat 8 are removed from the molding belt 7 and/or transferred to a refuse chute 16.

According to a sixth embodiment, the method according to one or more of the preceding embodiments characterized in that pneumatic nozzles 27 and/or a switching system 28 and/or a molding-belt retraction system 17 transfers the biomass 1 to a refuse chute 16 for separating the defective regions 25.

According to a seventh embodiment, the method according to one or more of the preceding embodiments characterized in that the biomass 1 of the mat 8 is disintegrated with the aid of a milling roller 10 at the end of the molding belt and/or by means of a disintegrating device 5 disposed upstream of the pelleting press 2 in the falling direction of the biomass.

According to an eighth embodiment, the method according to one or more of the preceding embodiments characterized in that biomass 1 is used that is sieved during its preparation to a size of more than 0.3 mm (screening mesh width).

According to a ninth embodiment, the method according to one or more of the preceding embodiments characterized in that the mat 8 made of biomass 1 passes through steam in a vaporization device 13.

According to a tenth embodiment, the method according to one or more of the preceding claims characterized in that the mat 8 is compacted on the molding belt 7 with the aid of a prepress 12.

According to an eleventh embodiment, the method according to one or more of the preceding claims characterized in that an extruder press, a two-roller press or an annular die comprising at least one inwardly or outwardly disposed pan-grinder roller is used as the pelleting press 2.

According to a twelfth embodiment, an installation for the production of pellets 9 from prepared biomass 1 in a pelleting press 2 for use as fuel in fireplaces, the biomass 1 being made of fibers, shavings or chippings containing cellulose and/or lignocellulose, with or without a binding agent and/or additives, and a biomass bunker 3 being disposed for the storage of the biomass 1 following its preparation, which installation is characterized in that, in the production process downstream of the biomass bunker 3, a scatter device 6 and a molding belt 7, which rotates horizontally endlessly in the falling direction of the biomass, is disposed at the discharge side of the scatter device 6 for producing a mat 8 having a substantially uniform weight per unit area, and an examining device 11 for examining defective regions 25 and/or foreign substances 26 in the mat 8 is disposed in the region of the molding belt 7, and at least one device for separating at least parts of the mat 8 or an entire section of the mats 8 is disposed for separating the defective regions 25 and/or the foreign substances 26 upstream of the pelleting press 2.

According to a thirteenth embodiment, the installation according to the twelfth embodiment characterized in that a weighing device and/or a radiography device is disposed as the examining device 11.

According to a fourteenth embodiment, the installation according to the twelfth embodiment or the thirteenth embodiment characterized in that a radiography device is disposed for determining the weight per unit area of the mat with a resolution of 1×1 mm for detecting defective regions 25 and/or foreign substances 26 in the mat.

According to a fifteenth embodiment, the installation according to one or more of the preceding embodiments characterized in that a molding-belt retraction system 17 and/or a suction device 31 and/or a removing device 32 are disposed in the region of the molding belt 7 for disposing of the defective regions 25 and/or the foreign substances 26 in a portion of the mat 8 or a section of the mat 8 in a refuse chute 16.

According to a sixteenth embodiment, an installation according to one or more of the preceding embodiments characterized in that pneumatic nozzles 27 and/or a switching system 28 and/or a suction device 31 is disposed in the further production process downstream of the molding belt 7 for separating the defective regions 25 and/or the foreign substances 26 in the mat 8.

According to a seventeenth embodiment, the installation according to one or more of the preceding embodiments characterized in that a disintegrating device 5 for disintegrating the falling biomass 1 is disposed between the molding belt 7 and the pelleting press 2.

According to an eighteenth embodiment, the installation according to one or more of the preceding embodiments characterized in that at least one disintegration roller formed preferably as a spoke roller 15 is disposed in the form of a disintegrating device 5.

According to a nineteenth embodiment, the installation according to one or more of the preceding installation embodiments characterized in that an extruder press, a two-roller press or an annular die comprising at least one inwardly or outwardly disposed pan-grinder roller is disposed as the pelleting press 2.

According to a twentieth embodiment, the installation according to one or more of the preceding installation embodiments characterized in that a vaporization device 13 is disposed in the region of the molding belt 7.

According to a twenty-first embodiment, the installation according to the twentieth embodiment characterized in that a screening belt is disposed as the molding belt 7 for the perfusion of the molding belt 7.

According to a twenty-second embodiment, the installation according to one or more of the preceding embodiments characterized in that a prepress 12 is disposed in the region of the molding belt 7.

The construction and arrangement of the installation and method, as shown in the various exemplary embodiments, is illustrative only. Although some embodiments have been described in detail in this disclosure, many modifications are possible without materially departing from the novel teachings and advantages of the subject matter described herein. Other substitutions, modifications, changes and omissions may also be made in the design, operating conditions and arrangement of the various exemplary embodiments without departing from the scope of the present disclosure. 

1. A method for producing pellets from prepared biomass in a pelleting press for use as fuel in fireplaces, the method comprising the steps of: preparing the biomass, the biomass being made of fibers, shavings, or chippings containing cellulose and/or lignocellulose; storing the biomass in a biomass bunker following the preparation of the biomass; discharging the biomass from the biomass bunker to a scatter device; forming, on a molding belt by using the scatter device, a mat made of the biomass and having a substantially uniform weight per unit area; examining the mat formed on the molding belt for defective regions and/or foreign substances using an examining device; supplying a first section of the mat to the pelleting press; and separating a second section of the mat having the defective regions and/or the foreign substances from the production of the pellets upstream of the pelleting press.
 2. The method of claim 1, wherein the examining and separating steps include determining and separating mat irregularities having properties that are detrimental to the pelleting press, the irregularities including the defective regions, the foreign substances, inhomogeneities, and/or excessive density.
 3. The method of claim 1, wherein the examining device comprises a weighing device and/or a radiography device.
 4. The method of claim 3, wherein the examining step includes using the radiography device to determine a weight per unit area of the mat in a grid of a square millimeter in order to detect the defective regions or the foreign substances.
 5. The method of claim 1, further comprising removing the second section from the molding belt and/or transferring the second section to a refuse chute.
 6. The method of claim 1, wherein the separating step includes transferring the biomass to a refuse chute using pneumatic nozzles, a switching system, and/or a molding-belt retraction system.
 7. The method of claim 1, further comprising disintegrating the biomass of the mat using a milling roller positioned at an end of the molding belt and/or using a disintegrating device disposed upstream of the pelleting press and in a direction in which the biomass falls.
 8. The method of claim 1, wherein the preparing step includes sieving the biomass to a screening mesh width size of more than 0.33 mm.
 9. The method of claim 1, further comprising passing the mat through steam in a vaporization device.
 10. The method of claim 1, further comprising compacting the mat on the molding belt using a prepress.
 11. The method of claim 1, wherein the pelleting press includes an extruder press, a two-roller press, or an annular die having at least one inwardly or outwardly disposed pan-grinder roller.
 12. An installation for producing pellets from prepared biomass in a pelleting press for use as fuel in fireplaces, the biomass being made of fibers, shavings, or chippings containing cellulose and/or lignocellulose, with or without a binding agent and/or additives, the installation comprising: a biomass bunker for storing the biomass following the preparation of the biomass; a scatter device disposed downstream of the biomass bunker; a molding belt disposed at a discharge side of the scatter device, wherein the molding belt is configured to rotate horizontally endlessly, and wherein the scatter device is configured to form a mat on the molding belt; an examining device disposed in a region of the molding belt, wherein the examining device is configured to examine defective regions and/or foreign substances included in a mat; and at least one device disposed upstream of the pelleting press, wherein the at least one device is configured to separate at least parts of the mat or an entire section of the mat that contains the defective regions and/or the foreign substances.
 13. The installation of claim 12, wherein the examining device comprises a weighing device and/or a radiography device.
 14. The installation of claim 13, wherein the radiography device is configured to determine a weight per unit area of the mat with a resolution of 1×1 mm for detecting the defective regions and/or the foreign substances in the mat.
 15. The installation of claim 12, further comprising a molding-belt retraction system, a suction device, and/or a removing device disposed in a region of the molding belt, wherein the molding-belt retraction system, the suction device, and/or the removing device are configured to dispose of the defective regions and/or the foreign substances of the mat in a refuse chute.
 16. The installation of claim 12, further comprising a pneumatic nozzle, a switching system, and/or a suction device disposed in a further production process located downstream of the molding belt and wherein the nozzle, the switching system, and/or the suction device are configured to separate the defective regions and/or the foreign substances in the mat.
 17. The installation of claim 12, further comprising a disintegrating device disposed between the molding belt and the pelleting press, wherein the disintegrating device is configured to disintegrate falling biomass.
 18. The installation of claim 17, wherein the disintegrating device comprises at least one disintegration roller including a spoke roller.
 19. The installation of claim 12, wherein the pelleting press comprises an extruder press, a two-roller press, or an annular die having at least one inwardly or outwardly disposed pan-grinder roller.
 20. The installation of claim 12, further comprising a vaporization device disposed in a region of the molding belt.
 21. The installation of claim 12, wherein the molding belt comprises a screening belt configured to perfuse the molding belt.
 22. The installation of claim 12, further comprising a prepress disposed in a region of the molding belt. 